Offset joint for downhole tools

Abstract

A variable offset joint is provided for downhole tools, including a first downhole member, a second downhole member, and at least one intermediate element pivotally coupled at a first end to the first downhole member and at a second end to the second downhole member. The variable offset joint further includes a coupler member adapted to maintain a predetermined lateral offset between the first and second downhole members. The coupler member further includes a zone of weakness adapted to fracture when a tensile force applied thereto exceeds a predetermined threshold. In one example, a plurality of intermediate elements are each pivotally coupled to the first and second downhole members. In another example, the coupler member extends between at least two of the plurality of intermediate elements. In another example, adjusting a length of the coupler member selectively adjusts the predetermined lateral offset.

1. A variable offset joint for downhole tools, including:
 a first downhole member; 
 a second downhole member; 
 a plurality of intermediate elements each pivotally coupled at a first end to the first downhole member and at a second end to the second downhole member; and 
 a coupler member extending between first and second of the plurality of intermediate elements, with a first end of the coupler member being pivotally attached directly to the first intermediate element and a second end of the coupler member being pivotally attached directly to the second intermediate element, and adapted to selectively maintain a lateral offset between the first and second downhole members, the coupler member further including a zone of weakness adapted to fracture when a tensile force applied thereto exceeds a predetermined threshold. 
 
     
     
       2. The variable offset joint of  claim 1 , wherein an effective length of the coupler member establishes the lateral offset between the first and second downhole members. 
     
     
       3. The variable offset joint of  claim 2 , wherein the lateral offset between the first and second downhole members is sufficient to accommodate a range of operation within a well having a diameter between about six inches and about sixteen inches. 
     
     
       4. The variable offset joint of  claim 1 , wherein the length of the coupler member establishes a predetermined angle defined between at least one of the first and second downhole members and at least one of the plurality of intermediate members to thereby establish the lateral offset between the first and second downhole members. 
     
     
       5. The variable offset joint of  claim 4 , wherein the predetermined angle is the range of about 5 degrees to about 45 degrees. 
     
     
       6. The variable offset joint of  claim 1 , wherein the zone of weakness includes a frangible neck sized to fracture when mechanical stress applied thereto exceeds a predetermined threshold. 
     
     
       7. The variable offset joint of  claim 6 , wherein the predetermined threshold is based upon a tensile force of about 2,500 to about 8,000 pounds. 
     
     
       8. The variable offset joint of  claim 6 , wherein the frangible neck includes a reduced cross-sectional area. 
     
     
       9. The variable offset joint of  claim 1 , wherein the plurality of intermediate elements are adapted to maintain the first downhole member generally parallel with the second downhole member. 
     
     
       10. The variable offset joint of  claim 1 , further including at least one electrical coupler provided to each of the first and second downhole members, at least one wire extending between the electrical couplers for communicating electrical current therebetween, and a sealed tubing enclosing the at least one wire and extending between the electrical couplers of the first and second downhole members. 
     
     
       11. A variable offset joint for downhole tools, including:
 a first downhole member; 
 a second downhole member; 
 a plurality of intermediate elements each pivotally coupled at a first end to the first downhole member and at a second end to the second downhole member; and 
 a coupler member extending between first and second of the plurality of intermediate elements, with a first end of the coupler member being pivotally attached directly to the first intermediate element and a second end of the coupler member being pivotally attached directly to the second intermediate element, and adapted to maintain each of the first and second downhole members at a predetermined angle relative to at least one of the plurality of intermediate elements, the coupler member being further adapted to fracture when a tensile force applied thereto exceeds a predeteunined threshold. 
 
     
     
       12. The variable offset joint of  claim 11 , wherein the coupler member includes a frangible neck sized to fracture when mechanical stress applied thereto exceeds a predetermined threshold that is based upon a tensile force of about 2,500 to about 8,000 pounds. 
     
     
       13. The variable offset joint of  claim 12 , wherein the frangible neck includes a reduced cross-sectional area. 
     
     
       14. The variable offset joint of  claim 11 , wherein adjusting a length of the coupler member adjusts the predetermined angle to thereby adjust a lateral offset between the first and second downhole members. 
     
     
       15. The variable offset joint of  claim 11 , further including at least one electrical coupler provided to each of the first and second downhole members, at least one wire extending between the electrical couplers for communicating electrical current therebetween, and a sealed tubing enclosing the at least one wire and extending between the electrical couplers of the first and second downhole members.